#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#define BUFFERSIZE 4096
#define COPYMODE 0644


void oops(char *, char *);

int main(int argc, char *argv[])
{
	int in_fd, out_fd, n_chars;
	char buf[BUFFERSIZE];
	if (argc != 3) {
		fprintf(stderr, "usage: %s source destination\n", *	argv);
	exit(1);
					}
	if ((in_fd = open(argv[1], O_RDONLY)) == -1)
	oops("Cannot open ", argv[1]);

	if ((out_fd = creat(argv[2], COPYMODE)) == -1)
	oops("Cannot creat", argv[2]);
	
	while ((n_chars = read(in_fd, buf, BUFFERSIZE)) > 0)
	if (write(out_fd, buf, n_chars) != n_chars)
	oops("Write error to ", argv[2]);

	if (n_chars == -1)
	oops("Read error from ", argv[1]);

	if (close(in_fd) == -1 || close(out_fd) == -1)
	oops("Error closing files", "");
}

void oops(char *s1, char *s2)
{
	fprintf(stderr, "Error: %s ", s1);
	perror(s2);
	exit(1);
} 
